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Official Journal of the fflll-i i iID • M~ l\¼i i =I ill,~ I•J

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NO. 4 -

DEC. 1974 -

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EDITORIAL COMMITTEE Chairman: C.D.Parker Committee: M. Dureau G. R. Goffln L. C. Smith F. R. Bishop R. L. Clisby Joan Powling B. S. Sanders A. G. Longstaff W. Burnett W. Nicholson A. F. Herath A.Macoun Publisher: Hon. Editor: A.H. Truman John G. Craig

BRANCH CORRESPONDENTS

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Official Journal of the !AUSTRALIAN WATER...Affru

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IIASTEWATER ASSOCIATION! ~ol. 1 No. 4

Dec. 1974

CONTENTS Editorial -

Wider Horizons? ............................................. 7

CANBERRA, A.C.T.:

A. Macoun, P.O. Box 306, Woden, 2606 NEW SOUTH WALES: M. Dureau, Envirotech Australia . Ply.Ltd., 1 Frederick Street, Artarmon. VICTORIA: A.G. Longstaff, Gutteridge Haskins & Davey, 380 Lonsdale Street, Melbourne, 3000.

Association News ................................................................ 8 The Westernport Bay Environmental Study - Maurice A. Shapiro .............................................. 9 Biological Chemical, and Related Engineering Problems in Large Storage Lakes of Tasmania - Henry H. McFie .............................................................. 14 Conference Calendar ......................................................... 18

QUEENSLAND: L. C. Smith, 24 Byambee Street, Kenmore, 4069.

Unique Water Supply Problems in the North West of South Australia - Dr. 0. Fullard and R. Shepherd ................... 19

SOUTH AUSTRALIA: R. L. CLlsby, c/-E. & W. S. G.P.O. Box 1751, Adelaide, 5001.

Construction of the Molonglo Valley Interception Sewer (M.V.I.S.) ............................................ 21

WESTERN AUSTRALIA: B. S. Sanders, 39 Kalinda Drive, City Beach, 6015. TASMANIA:

P.E. Spratt, C/o Fowler, England & Newton, 132 Davey St., Hobart, 7000 NORTHERN TERRITORY: A. F. Herath, 59 Allwright St., Casuarina, 5792. Editorial Correspondence: Hon. Editor, A. H. Truman, c/- Davy-Ashmore Pty. Ltd., P.O. Box 4709, Melbourne, 3001. Or to State Correspondents.

Advertising Enquiries: John Craig, 'Water' P.O. Box 100, Caulfield East, 3145 Phone: 211 7978 - 874 2133

Subscriptions and Membership ........................................ 22 INSTRUCTIONS TO AUTHORS Articles should be of original thought or reports on original work of Interest to the members of the A.W.W.A. and preferably not more than 5,000 to 7,000 words. Full Instructions are available from Branch correspondents or the Editor.

FRONT COVER: Waste Water Treatment section of a complex designed and installed for the Army Jungle Training Centre in Queensland by Pettigrew Eng in ee ri ng. The complete system includes initial Water Treatment Plant for supply of 4 mil li on litres per day, followed by ful l ret iculation , and terminating in the Waste Water Treatment Plant il lustrated. Waste Water Treatment Plants of the type shown are capable of produci ng treated water of super ior quality to the natural water course receiv ing the discharge. A number of plants already operat ing throughout Austra li a are capab le of treating waste water to a high standard su itable for recycling. Many more opportunities exist for re -use of water at considerab le cost saving to communities and ind ustrial interests and these must rece ive increasing attention . Pettigrew Engineering is one of the organisations giving active atten tion to research and deve lopment in this fie ld of recycling w hi ch is a grow ing responsibility of Water Treatment Engineers.


THE WESTERNPORT BAY ENVIRONMENTAL STUDY

WESTERNPORT BAY ENVIRONMENTAL STUOY LOCATION Of

SAM,l!NG STATIONS IN

THC

BA Y

Maurice A. Shapiro Study Di rector Westernport Bay is one of those historical misnomers - it is the eastern of the two major bays in the Melbourne region. It was named by that intrepid physician George Bass, who discovered it in 1798, when he sailed south from Botany Bay in an open whaleboat. It was the westernmost bay he found on his voyage of exploration. Just a few miles to the west, over the Mornington Peninsula, he could have found what is now called Port Phillip Bay, a larger body of water and upon whose shores ttie majority of Victoria's population reside (2.5 million in the Port Phillip Bay catchment and 50,000 on the Westernport Bay catchment). Located about 50 km from Melbourne at its closest point , the water area be low th e high water mark is 680 km ' with a large system of wide drying tidal flats drained by an extensive system of naturally deep channe ls . Th e mudflats are substantially covered with seagrasses of a number of species and fringed with Saltmarsh and mangrove communities. The tida l rang e is 1.9 m and tidal currents exist. However, the distance of the main body of water from Bass Strait results in a relatively low rate of tidal interchange . Phi ll ip Island protects the Bay from Bass Strait and Frenc h Island occupies the centra l area. The Westernport region is noted for its birdlife. In this area (less than two per cent of the State) nearly half (200) of the 470 species of birds found in Victoria have been reported . Such a diversity in a relatively small area is not common in the State. The whole region provides bird habitats but the swamps , marshes , mangroves , mudflats and bay waters are of particular importan ce. French Island alone has been estimated to support more than 1,000 pairs of breeding ibis . Also important are ducks , swans , pe licans , short-tailed shearwaters (mutton birds} , penguins and a considerab le range of waders and water fowl. The area is also noted for the wildlife it shelters. Near Tyabb a small co lony of the New Holland mouse , previously thought to be extinct in Victor ia, was re cent ly re-discovered . The only previ ous record of the mouse in the State was from fossil remains found in the Buchan district in eastern Victoria. Another small anima l, the Potoroo or rat kangaroo, which was thought to be almost extinct in Victor ia has been found in large numbers on French Island . Phillip Is land on th e Bass Strait side , is one of the most important wi ld life areas in Victor ia. It conta ins a large koa la popu lation and is the most important sing le area in the koala management program of the Department of Fisheries and Wildlife. An extensive Fairy Penguin rookery at Summerland is protected and it is here at dusk that the famous pengu in parade may be seen. The large mutton bird rookeries are also protected. Unrestricted sealing during the 19th centu ry decimated the seal population , but now protected , the most readily accessib le and observab le seal co lony off the Victorian coast is located at Seal Rocks just off the Island . But it is as a recreation area that Westernport is best known . Although Phi ll ip Island with its unique fauna , is a true international tourist attraction , it is the Mornington Peninsula that has become the inajor recreation outlet for metropolitan Melbourne .

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Separating Port Phillip Bay and Westernport , and located immediately to the south-east of the metropo li s, the Peninsula is an area of great natural attraction containing a variety of recreation resources . Its landscapes form a mosaic of hill and vale, wood and pasture; its beaches range from the safe , sandÂĽ beaches of Port Phillip Bay to the wave -swept surf beaches of the Gunnamatta-Portsea area . A third of the houses on the Peninsula are holi day homes and some 150,000 people use the area as their main sou rce of recreation during the peak summer months . Both Port Phillip Bay and Westernport are extensively used by amateur fishermen , yachtsmen , swimmers and power boat enthusiasts. Westernport also supports a commercia l fishin g industry which supp li es a large proportion of Melbourne 's fish requirements . The bay is fringed with small towns - San Remo , Corinel la, Tooradin , Warneet and Hastings - which have , in the past, been almost totally dependent upon the fishing industry. Westernport Bay has long been recognised as a fine port with deep, sheltered anchorage but it was adjoining Port Phillip Bay which became Victoria 's major commercial and industrial port. Now wit h a dramatic in crease in deep draught shipping , particu larly for industrial cargoes, the importance of Westernport has in creased. No other harbour on the Victorian coast , and few in Austra lia , can match its deep sheltered waters. Almost comp letely landlocked , its depth at the entrance exceeds 33 metres , dropping to a minimum at low water of 15 metres in the No rthern Arm and 16 metres in the Western Arm. Three major industries , a refinery , a crud e oi l and L.P.G . export facility and the first stage , a co ld reduction mill , of a proposed integrated steel wi ll have been established on the Western shore of the North Arm . The two petroleum facilities are served by channels and port facilities accommodating tankers up to 100,000 D.W .T. Both jetties are owned by the State of Victoria while the raw materials for the cold reduction plant are handled on roll-on , roll-off berths bui lt by the industry concerned . Th e Acts passed to facilitate construction of two of the industries allows them to carry out reclamation on the Bay shore and some areas have already been created.

Foo tnote : Pro fesso r Shapiro w ll l return to his pos it ion as Profess or Envi ro nmen tal Health Eng ineering & Urban Affairs . Universit y of Pittsburgh . early

in

1975

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Other factors add to Westernport 's va lu e as an industria l port . In the vicinity of Hastings, the deep water .channel is flanked on both sides by larg e tracts of flat land suitab le for heavy indu stria l development. It is c lose to the Melbourne-Dandenong-Berwick axis , where the thrust of Melbourne 's growth is greatest . Simi larly, it is c lose to the Melbourne-Gippsland ax is wit h its ric h resources , such as th e extensive brown coa l deposits in the Latrobe Vall ey and the recoverab le gas and oil in Bass Strait. In t he mid dle sixties local governments and the Governmen t of Victoria were advocating extensive deve lopment of the port and new indu stries and there was pressure for major rec lamat ion of th e tida l flats of th e Bay- all with litt le recogni ti o n of the possib le env ironmenta l consequences. The large labour and consumer market of Melbourne is nearby , and the region is central to the entire market of south-east Austra lia. It is also wel l serve d by land transport connections. In th e competitive striv ings of in dustry, t ransportat ion costs are particularly important. Some industries cannot ex ist wit hout c lose access to deep wate r and the economies of deep draught bulk cargo shipping . M any of these indu stri es are basic to Australia ' s economy. Only Westernport on the Victorian coast and a small number of other locations on the entire Australian coast possess the qualities whi c h are esse nti al to these industries . When the fac tors of markets , labour, deep water, land quality and avai lab il ity, and raw material sources are analysed , Westernport is found to be a most suitab le si te for the deve lopment of an in dustria l port comp lex . Perhaps the most im portant feature of the reso urces of Westernport is that they do not exist in iso lation. Th ese resources are linked in an ecological system such that the value of each resource is related and often de pendent upon the maintenance of the ot hers. That is why, wit h mu ltiple pressures fo r exp lo itat ion of Westernport , it is deemed essential that deve lopment and conservation go hand in hand .

The Study By 1970 the concept of a major mu ltidi sci plin ary stud y was accepted by all concerned and the out lin e of its form established. The overall responsibi lity for the Study is lodged in a four man Execu tiv e Comm ittee chaired by th e Deputy Director in the Ministry for Conservation. The three remaining members represent the Westernport Regional Planning Authority , the Division of Ports and Harbo rs and an industry re prese ntat ive. It has been ave rred that the Study has unique features - perhaps of greatest moment is the fact that of the current $1.535 million $400 ,000 is a contributi on from indu stry. Howeve r, the Stud y is indepe ndent and , sub ject to the admin istrative policy of governmen t being genera lly adhered to , all policy decisions and financial approvals are matters for he Executive Committee. Th e Executive Co mmittee is backed by a larger St udy Commi ttee , c haired by the Pro Vice Chancellor of Monash University , which has a major function of co mmenting on proposed tasks prepared by ad hoc sub committees and , since the advent of the Co re Group- th ose prepared by them. Recently, a Review Committee was appo inted with the function of acting outside the already existing bodies to assess progress and objecti ves of the Study and report to Government. Early in the development of the Study it was co ncluded that the demands of a mu ltidi sc ipl inary undertaki ng required direction and co-ordination. The Co re Group concept evo lv ed and was accepted. This is, as is the Study itself , a group composed of biological, ph ys ica l and soc ial sc ient ists , engineers and ad mini strators . The Core Group is intimate ly invo lved in eac h of the research and investigation projects , and is responsib le to the Execu tive Committee. The Westernport Bay Environmental Study is a cooperative and co ll aborat ive effort consisting of basic an d applied research activ ities desig ned to develop com prehensive know ledge and understandiflg of the Bay and its catc hment so that a balanced approach can be made towards the future of Weste rnpo rt Bay and its region. A ba lanced approach shou ld permit those with statutory responsibilities and others concerned , to assess and evaluate most , and ideall y, all of the relevant factors whi c h imp ing e on the enviro nm ental viabi li ty of Westernport Bay and its catchme nt .

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Cooperation and co llaboration is demonstrated in a variety of ways , but perhaps the most unique is the fact that it is jointly financed by government and industry. The original budget, approved in 1972 , amounted to $1 million ; $300,000 prov ided by in dustry and $700,000 by government. Early in 1973, a budget review was undertaken to update scient ific information and take into accou nt oth er c hanges such as inflatio n . This resu lted in approval of a new budget of $1.535 million to which industry and government contributed on the same basis as was ag reed for the origin al budget . Th e Study , originally co nceived as a five year activity with a maj or report to be submitted at th e end of the first tw o and one half years , is cu rrently a two year project . When con fron ted with the rea li ties of the situation the Study Committee and the Executive Committee agree d to a possibility of undertaking a study wit hin two yea rs . Thus , all of th e contracts awarded to university groups and cons ultants, and the task specificat ions app roved for th e st udi es and researc h undertaken by governmenta l agencies i.e. the Department of Ag ri cu lture, the M arin e Po ll ution Stud ies Unit of the Fisheries and Wildlife Department , State Riv ers and Water Suppl y Commission , Port s and Harbors Di vision of the Department of Pub lic Works, th e Bureau of Mines and C.S. I. R.O. - all have deadlines for a final or major re port to be submitted no late r than the third quarter of 1974. Th e latter requirement is for those projects which have a longer co ntrac tu al life th an the two years , or first phase of the Study. Shortly after the Study was initiated , the Premi er of Vi cto ri a , o n 13 February 1973, made a statement co nce rnin g the future of the Mornington Peninsu la and Westernport. The first of the five poin t s of the statement was: " 1. No permits fo r major industria l project s in the Westernport area (including French Island) will be granted while the study is in progress (at least for two years). " (The Study is the Westernport Bay Environmental Study) By this act ion the requirement for the submission of a report at the end of the two year study was re-emphasised. The Study wil l soon enter the th ird quarter of its two year life. From the original twe nty three tasks speci fi ed , the Study has grown so that at present the fo ll ow ing ac tivities or pro jec t s are underway :

1. Land Based Studies Land based studies are designed to o bt ain basic infqrmat ion and understanding of the physical characteristics of th e catchment , its so ils , geology , hydro logy and th e c lim atology . Th e latter informat ion is to be obt ai ned¡ from historical records and current measurements. 1.1 Geology 1.1.1 Description of Geology and Hydrology of the Bay sembli ng and evalu at in g the exist in g informatio n

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1.1.2 Gravity Survey- to determine th e regional exten t of th e various geological features in the Westernport Sunkland s.

1.2 Soil 1.2. 1 Soil reconnaisance survey - to map the so ils in the catchmen t and determin e th eir suitabi lit y for forest , agriculture and urban use , their physical and chemica l properties affect ing run-off and grou ndwater flow. 1.3 Climate 1.3.1 Climate Survey -

Rainfall , ev aporation and run-off .

1.4 Air Quality 1.4.1 Air Quality Baseline Investigation - to determine the air po llution potential of the Westernport region with partic ul ar em ph asis on the areas presently proposed fo r industrial development . 1.5 Inputs to the Bay 1.5.1 Input Stream Samp lin g and Gaug ing - to deve lop in fo rmation on the current annual loads of substances entering the Bay land. 1.5.2 Pesticide Determinations - to develop esti mates of the inputs of pestic ides and herbicides into Westernport Bay .

1.6 Land Use Existi ng Land Use in the Catch ment - Mapping the c urrent land use patterns in the catc hment of Westernport Ba y.


2. Marine Studies Marine Stud ies are designed to obtain the maximum information and understanding possible under the constraints of time and resources about the physical, chemica l and biological regimes of the Bay. They constitute collaborative field sampling and collection programs , laboratory analysis and research activities . They range from categorization of archival bio logical material collected by a large number of people for many years and stored in the Nationa l Museum to " flow through" toxicological studies conducted by the Marine Po ll ution Studies Division designed to ascertain the lethal and sublethal effects of toxic materials which cou ld be introduced into the Bay . 2.1 Physical Characteristics of the Bay 2.1.1 Hydrographic and Hydrodynamic Characteristics Study to obtain basic hydrographic and hydrodynamic data for ca librat ion and ver ificat ion of the Water Quality Model and to provide a comprehensive description of water movement in the Bay . 2. 1.2 Drift of Surface Residing Materials Study - to describe the patterns of surface winds in the region and to deve lop, as an adjunct to the Water Quality Model , a techn ique to determine the likely frequency of deposition on shores of the surface residing materials discharged from any potential source . ¡ 2. 1.3 Preliminary Sediments Survey - to obtain a preliminary assessment of the patterns of sediment distribution in th e Bay. 2.1.4 Sediment Movement and Bottom Deposits Bottom current and sediment transport at selected localities. Bottom drift stud ies to predict the occurrence of sediment movement and determine mode of sediment transport. 2. 1.5 Sparker Seismic Survey - to de lineate the subsea extent of aquifers in the area and to locate any sea bottom outcrops of these aquifers where salt water intrusion or fres h water loss may be occurring.

2.2 Chemica l Characteristics of the Bay 2.2.1 Nutrient and other chemical studies To determine the concentrations of nutrients and other chem ica l substances of env ironment impo rtance and their seasonal variations in the Bay waters. 2.2.2 Environmental Monitoring of Toxic Materials Th e object ive of this program is to investigate the current d istribution and concentration of pesticides , P.C.B 's and heavy metals (Zn , Cd , Pb and Cr) in sediments, phytobent hos, zoobent hos , total plankton , water , fishes , birds and mammals at major river, municipal and industrial effluent discharge points in Westernport Bay . 2.2.3 Investigat ion of Organic Substances Survey of the concentrations of hydrocarbons in the North Arm of the Bay.

2.3 Population and Community Structure 2.3.1 Fie ld Survey of Fish Popu lat ions To estab lish base line data on fish popu lations in the Bay inc luding characterization of natural variation agai nst wh ich future changes can be assessed. 2.3.2 Zoop lankton Population Studies To determine existing types , abundance and distribution of zoop lankton in Westernport Bay . 2.3.3 Zoobenthos Invertebrate Studies 1. To provide info rmation as to the present condition of the Bay by surveying the invertebrate population in order to develop estimates of the density and diversity of this popu lation. 2. To obtain knowledge of the distribution of benthic fauna and any relevant physicochemical parameters wh ich is sufficient ly detailed and qualified to provide a base line against which changes in fauna l composition can be evaluated . 2.3.4 Study of Arch iva l Benthic Material To assist in the definition and characterization of the mari ne invertebrate fauna of Westernport Bay by cor-

relatting the records and co ll ections lodged in the National Museum of Victoria archives over the past eighty years , with new information being obtained by the Marine Pollution Studies Group. 2.3.5 Avifauna Investigation - To collect historical and current data on the species associated with the various habitats in the area and , as possible, to determine the seasonal variation in habitat usage and abundance of species . 2.3.6 Preliminary Investigation of the Effect of Dredging and Dredging Spoil - To evaluate the effects of past dredging and spoil disposal in Westernport Bay and to indicate whether or not further investigation is needed into the effects of dredging operations on the biological en vironment of the Bay.

2.4 Mangroves, Seagrass, and Related Studies. 2.4 .1 Study of Coastal Dynamics Historical data indicates that sedimentation, erosion and other factors have caused substantial changes to the coastline of Westernport Bay . This study is designed to provide one input for the development of guidelines for management of future coastal changes . 2.4 .2 Classification and Mapping of Peripheral Vegetation To survey and map the coastal vegetation of Westernport Bay and to determine the vegetation units or plant associations that exist in this region . 2.4.3 Mapping of Seagrass Communities To provide basic information as to the extent and location of the seagrass communities in Westernport Bay. This information is needed by the other studies concerned with the quantative evaluat ion of the biological significance of the mangrove , saltmarsh and seagrass communities . 2.4.4 The determination of the Role of the Mangrove and Seagrass Communities in Nutrient Cycling The purpose of this investigation is to examine the cyc ling of nutrients within and between plant communities in Westernport Bay. 2.4.5 Study of the Role of Macrofauna in Seagrass Communities - This project aims to concet1trate on a limited number of representative areas and carry out detailed studies on these areas in order to determine the role of the seagrass macrofauna in the Bay ecosystem . 2.4.6 Marine Bacteria Investigation To investigate the ro le of bacteria in controlling the rate of breakdown of marine organic matter and the cycling of nutrients in Westernport Bay . (Carried out in parallel with a simi lar investigation in Port Phillip Bay .) 2.4 .7 Study of the White Mangrove (Avicennia marina). To determine the environmental factors controlling growth and survival of the White Mangrove (Avicennia marina) in Westernport Bay . 2.4.8 Product ivity Studies Work has begun on the study of carbon flux through the Bay system in relation to nutrient cycling. Production of organic carbon by seagrasses and phytoplankton is being compared and an assessment of less thorough respiration versus consumption in situ , in open water, sed iments, loss to beaches and open ocean is being made.

2.5 Toxicology and Related Studies 2.5.1 Fish Toxicology Study The fish toxicology program is designed to establish the "safe " ambient concentrations of selected heavy metals for the species of fish in Westernport Bay that are important for commercial , recreational and /or ecological reasons . It involves both static and flow-through bioassay experimentation. 2.5.2 Invertebrate Toxicology Study In this work the bioassay technique is being used to establish " safe " concentrations of toxican t s for invertebrate marine animals which occur in Westernport Bay. 11


2.5.3 Heavy Metal Accumulation in Biological Materials This work involves the col lect ion of phytoplankton from Westernport Bay and the analys is of these col lections for heavy metals (copper, zinc , lead and cadmium). In addition , laboratory cultures of Ditylum brightwellei are being made to determ in e the rate of uptake of the above heavy metals by thi s organism. 3. Social and Economic Studies Westernport Bay and its catc hment is a complex region. The future of the Bay and the region depends upon the quality of the choices and decisions made re its development. An understandi ng of the underlying social and economic determinants of suc h c ho ices is of great importance. The fo llowing projects , including the model building efforts, are designed to make a start in understanding the complex and ecological interrelati onships in the region. 3.1 Land and Bay Activities 3.1.1 Survey of existing land use The aim of this investigation is to co ll ect data on existing land use in the Westernport Bay catc hm ent and to arrange this information in a form appropriate for use in the land activities model.

3.1.2 Beach survey The aim of the beach survey is three fold . 1. To locate the present ly used beaches in Westernport Bay.

4.1.2 Water Quality Model To develop a mathematical model of Westernport Bay capable of linki ng discharges from the land to co ncentrations of several parameters in the Bay. The programs are to solve the basic equations of fluid flow and c hemical kinetics at each of the tho usand p lu s grid po ints throug hout the Bay . The programs are: 1. Topographic program 2. Hydrodynamic program 3. Pol lut ant transport program 4. Po llutant decay program 5. Pollutant Interaction and che mical kinetics program 4.2 .2 Water Quality Control Program Evalu ation of feasible alternative schemes for the collection , treatment and disposal of wastewater generated w ithin the catch ment.

5. Public Information 5.1 Final Report a. Summarised version b . " The Final Report " c . Reports of stud ies , invest igat ions and model development.

5.2 Film Production of an educational film of the Study .

2. To select representative beaches to be inspected regularly to assess present beach and water quality , present use , and any relations between these .

5.3 Public Meetings -

3. To gather data to form a basis for monitoring future changes in beach use and quality.

5.4 Talks to Groups Invited talks .

3.1.3 Forecast of possible industrial development To explore the econom ic probabilities and the types of industries locating at Westernport . 3.1.4 Survey of beneficial uses of the bay Th e m ain aim of this survey is t o provide suffi c ient quantitative documentation of both existing and the foreseeab le uses of the total study area to enable imputation of the public demand for them to be made . 3.2 Sociology 3.2.1 Sociolog ical investigation Th e aim of this investigation is to determine peoples attitude to aspects of the ex isting and projected environment of Westernport Bay and its region. 3.3 History 3.3.1 Hi story of th e Study area 1. To establish the pattern of sett lement of the Westernport region and discover any inf lu ences this had upo n comm uni ty development, transport pattern and use of natural resources.

2. To investigate the pressures, as they deve loped , from the growth of Melbourne and from concepts of Westernport as a setting for a separate urban -industrial centre, in particular those from 1960 to the present. 4. Development and Application of Models. 4.1 Land and Bay Activities 4.1. 1 Land Activ ities Mode l The aim of this model is to represent the relationshi ps between land activity alternatives , effluent c ontro l options and water quality in Westernport Bay and to take into co nsiderati on the soc ial and actual cost s and benefits of these options. - It is intended as a too l to permit exploration of the alternatives and to find a mix of act ivities whi c h can be defended on broad soc ial grounds , and to provide a basis for a wide r consens us in the commun it y as a who le.

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Schedu ling of public information meetings.

Research projects and in vest igations as part of the Study , were initiated early in 1973. Since that time more than thirty individuall y identifiable projects have been organised and are now (June 1974), when the Study is nearing the three quarter mark of Ph ase I, we ll underway , and some are actual ly nearing comp letion . A Critica l Pat h Program has been in ope rati on sin ce the Study was initiated and the network has been assessed a number of times. To illust rate the nature of individual projec ts three exampl es are described below The first , the Study of Coastal Dynamics is concerned with the nature and extent of the changes whic h have taken place on the shore lin e of Westernport Bay since the days of t he first exploration . This study consists of an evaluation of historical evidence, maps, aerial photographs coup led with a current air reconnaissance and new air ob lique ph otograph s. The latte r photographs allow se lection of cr itica l sites for further field examination of the form of the shoreline , the nature of associated sediments and vegetation and features indicative of changes now in progress in this im portant zo ne of th e Bay . Thi s investigation wi ll allow delineation of the types of change that have taken place and the formulation of hypotheses as to their cause. The field work has been comp leted and the results are being evalu ated. Another project of major proportions requ ired the development of a new laboratory unit within the Department of Agricu lture. This laboratory, designated the Marine Chemistry Unit , is respo nsibl e for the analysis of all of the samples co llected in the Bay as we ll as those derived from the tox ico log ica l inv estigations , etc . The determination of the chemical parameters is an essential requirement in the elucidation of understanding of the Bay system components . Th ese data are req uired if we are to progress towards an understanding of t he eco log ica l system of the Bay and fulfil the aim of developing an " ecological leader" . The individual determinations when assemb led and analysed deve lop ou r knowledge and understand ing of the distribution of sa lin it y, tota l phosphorus and nutrient salts, sili ca , ammonia, nitrite and nitrate . A pre liminary ana lysis of the chemical data obtained indicates that a major portion of the Bay is wel l mixed and that durin g the period of samplin g reported vert ica l gradients were found on ly in the lower part of the East Arm . A note of cau-

, l


tio n is indicated in read ing suc h co nc lusions . As in the case of biolog ica l informat ion , a sing le year of samp ling can not provide a co mplete pic ture of the chemica l regime in the Bay . For example , a very d ry season or yea r wil l present significantly different salin ity dist ribut ion patterns than those found in a very wet year. Ana lys is of the data obtained is proceeding and it is possible to discern ce rt ain other patterns , such as the expected strong corre lation between d isso lved oxygen concentrations and temperature. Two major mode ls are being developed in order that , through the ir use , changes in the Westernport system can be evaluated. Th us , the Water Qual ity Mode l is to be used in predicting the resu lts of int roduci ng po llutan ts into the Bay. The Land Ac tivities Mode l is des igned to provide a bas is for evaluating guidelines for the future deve lopment of the catchment of Westernport. It is be in g deve loped as a li near programm ing mode l in which it should be poss ible to evaluate what the economist terms the opportun ity cost of perusing one po li cy wh ich then can be conside red the loss of benefits that could be obtained from an alternative po li cy. Th e mode l, subject to stated assumptions whi c h wi ll be desc ribed in its format, and which can be varied by the user in app licat ion of the model, is a too l whi c h wi ll indicate how stated o bj ect ives can be attained at the lowest cost in terms of other va lu ed object ives. The deve lopment of the Land Act ivities Model and the Water Qua lity Mode l, wh ich consists of five linked programs , is des igned to sim ulate the tida l and wind induced motion of waters in the Bay , the diffusion , d ispe rsion and transport of materials such as disso lved oxygen , various forms of nitrogen , carbon , bioche mi ca l oxygen demanding material, temperature , etc . is well underway. Th e Land Activ ities Mode l has been developed and testing and trial runs are be ing conducted at present . The Water

ASSOCIATE NEWS CONT. 30th May: Pro fessor J . W. Ho lmes , Flinders University and Dr. G. Al li son , C.S .I. R.O . " Isotop ic Invest igat ions of Water and Water Resources of the SouthEast " . 22nd August: Speaker to be nom inated on a subject on the general top ic of " Meteoro logy and water " . 31stOctober : Lad ies Ni g ht at whic h se lected films on water wi ll be shown.

Quality Model topographic section has been comp leted and the hydrodynamic portion is we ll underway. Although recruitment and arrival of staff has , at times , been slow the general progress of the more than thirty projects has been generally within the desired limits . Mounting a comp lex and varied undertaking such as the Westernport Bay Environmental Study is major effort . Without the assistance and collaboration of a large group of dedicated peop!e it wou ld not be possible to c omplete it in two - or for that matter - five years. To c omp lete the studies and research on schedule demands the cooperation and dedication of a large and d iverse aggregation of individuals and organisations. It is g ratifying to report that the contractors, private and un iversity , the co ll aborating governmental agencies and the core group are all working very hard to meet their individual dead lines. As ment ioned previously the most recent addit ion to the Study is the Committee of Review. The Committee 's terms of reference are : " To review Study objectives by making impartial assessment of programs , agency , consu ltant and university contractor activity and advising upon these . " To report to Government on the organisation , operat ion and effectiveness of the Study. " From this time on our efforts will be bent toward two major objectives first , completion of the specified tasks , studies and research on time and second , to evaluate and integrate the in dividu al resu lts into a logical and coherent report that fulf ils the aims of the Study . The fina l report th is phase of the Study is due at the end of the first two years namely , as soon after December 31 , 1974 as possible .

NEW WATER POLLUTION CONTROL WORKS FOR THE PINE RIVERS SHIRE COUNCIL, QUEENSLAND

Designed by consu lt ing eng in eers John Wi lson and Partners of Brisbane , the first stage plant w ill handle wastes from 12,000 people. It wil l be operated ini tiall y using the extended aerat ion process but wil l be converted short ly to a convent ional (from Lyndsay Smith -Queensland act ivated sludge plant. By the add it ion of correspondent) primary sedimentation and sludge d igesThe Pine Rivers Shire Council has re-· tion the capacity wil l be increased to cent ly commissioned the first stage of a 32 ,000 peop le. water po ll ut ion control works which will Air , c leaned by ultra-fi ltration un its , is ultimate ly hand le domestic and industrial supp lied to some 4,000 A lundum dome wastes from a population of 250,000 peodiffusers in the aeration tanks by three ple . The plant is situated at Bick le Road , Hick Sutorbil t blowers driven by thyristor Kallangur adjacent to the mi ll of Austra lian control led variab le speed DC motors Paper Manufacturers Limited . manufactured by ASEA. One blower can deliver up to 2,400 s.c.f.m . with two smaller b lowers capable of de liver ing 1,200 s.c .f .m. each . The 15/15 standard effluent w ill be used by APM to prov ide the nutrients lack ing in its own mil l effl uent and thereby improve the standard of that effluent , at the same t ime reduc ing the flow of nutrients into the North Pine River. Graham Evans & Co. Pty. Ltd were the main contractors for the civ il wo rks which were constructed at a cost of some $790 ,000. Equipment contractors were EPCO Pty . Ltd . and th e cost of the equipment amounted to $240 ,000.

©omp liments of tl1e , e11so11 to ull our Jffilembers , !',ssoci11te "GUESTS AT THE ANNUAL LADIES NIGHT S.A. BRANCH" from left to right: Moss Saunders (Sect.), K. Trevarton (Pres.), Mrs. S. Kawamura, Mr. S. Kawamura (Sr. Engi neer, Water Treatment Division, James M. Montgomery Consulting Engineers, Inc. and Project Engineer for E&WS Anstey Hill W.T. Works Project), Mr. B. G. Stone (V. Pres., James M. Montgomery) and guest speaker for the evening Roger D. Stokes (Asst. Eng. for Water and Sewage Treatment - E&WS).

JIN embers

1111d reuders,

'mfirougfiout !',ustr11li11 1111d ®uerseus_ '&fie

lf ditor 13


Biological, Chemical and Related Engineering Problems in Large Storage Lakes of Tasmania HENRY H. MCFIE Civil Engineering Branch Hydro-Electric Commission Hobart, Tasmania, Australia MANAGEMENT AND DEVELOPMENT CONCEPT The Tasmanian Hydro-Electric Commission has seven man-made lakes with capacities of > 124,000,000 m3 ( > 100,000 acre-feet) and an additional three under construction (Table 1, Figure 1). The Hydro-Electric Commission has also built and operates for power production 21 smaller lakes, and two more are under construction. The commission is an autonomous governmental power utility that is responsib le to the state leg islature through the appo inted minister (the Premier) for power production , reticulation , and sales. With the exception of several small residual mining installations the comm ission investigates , designs , constructs , and operates the Tasmanian power system and associated works by using its own staff and resources except for some special contractua l activities. Until recent ly, generation was almost exclusively water powered , the first units being installed in 1895. The economical ly advantageous water power sites and the commission 's policy of using its own resources for the development of these sites have resulted in a long and continuous . engineering experience in these fields and a high growth rate of low-cost power with a strong metallurgica l base load. Because of these factors , power deve lopment has dominated water use in Tasmania for the past 50 years and has required the construction of large storage lakes from whic h secondary benefits of con siderable va lue have resu lted . However, Tasmania 's 33 man made lakes have been largely unipurpose in concept , legislative enactment , and operation . The construction of these storages and the various aspects of the management of t heir catchments involve the Hydro-Electric Commission with other governmental and semi -governmental agencies, name ly, the Forestry, Inland Fisheries , Rivers and Water Supply commissions ; the departments of Agriculture , Public Health , Tourists , Public Works (principal roads and bridges). and Lands and Surveys ; the Animals and Birds Protection Board , Scenery Preservation Board , and Rural Fires Board ; and rura l counci ls, private landowners, and common interest organizat ions . The more remote areas , which include the catchments of the tabulated lakes, are largely Crown lands including

forestry reserves and national parks together with limited leaseho ld and private ly owned lands used for their timber products and summer grazing . In these regions , large areas have been acquired by or vested in the Hydro-Electric Comm ission over which fee simple rights are exercised . GENERAL ASPECTS BecausEi of clearing costs of Aust$25 ,000-50 ,000 per square kilometer (Aust$100-$200 per acre) the majority of the storages are not cleared prior to flooding. Clearing is restricted to small areas adjacent to the damsites and to certain perip eries , and partial burning of the felled debris is the practice. Stands of dead trees and scrub occur in many lakes, and this timber , both standing and fel led , a long with the understory and the low flora and peats of the marshy plains provides adequate source material for an intensive biochemical activity, anaerobic cond itions occ urring in the thermally stratified lakes . The quantities of material involved , their decay rates , and the likely long-term effects have not been studied , but the persistence of these drowned and reexposed trees can be observed at Great Lake where , although they are diminishing in numbers , dead trees are sti ll standing after 40 years . With the exclusion of Lakes Rowa ll an (1967) and Barringto n (1969) where immediate and stable thermal stratification has occurred and Lake St. Clair where a thermocline is indicated but supporting data are lacking, there is no evidence that stratification occurs or has occurred in any storage of the Hydro-Electric Commission . It appears that any other thermoc li nes that may have occ urred were of short durat ion and have not caused noticeable effects (such as hydrogen sulfide) in bottom discharging out lets or in the occasional release of bypass water from lowlevel valves in the terminal diversion dams with high -level power outlets . Other than the bypass requirements , single-leve l out lets have been installed . Their location is determined by the operational range of the storage , some headwater dams having no usefu l lowlevel outlet . This type of installation results from the high costs associated with mu ltileve l outlets and at present the absence of economic justification. A maximum surface-water temperature of 18°C is within the tolerance limit for cold-water fish. Apart from the recent stratification effects, the acidic low-solid surface waters from the reservoirs have caused corros ion problems in hydraulic machinery and pipe lines. These prob lems have been caused principally by the tuberculation of stee l with penetration rates of 0.1 -0.2 mm /yr (0.004-0 .008 in ./yr) and by attack on zinc , copper , and aluminium together with extensive manganese bacterial slimes in closed conduits (principall y the

TABLE 1. Large Man-Made Lakes of the Tasmanian Hydro-Electric Commission Full Supply Normal Level Operating above msl Range Storage Lake Great Lake Arthurs Lake Lake King Wi ll iam Lake Lake Lake Lake Lake Lake Lake

14

St. Clair Ec ho Rowallan Barrington Cethana Pedder Gordon

meters

meters

1023.7 1030.2 1033.6 943.2 952.2 713.8 719 .9 736.7 846.4 487 .7 121.9 221 .0 308.5 307 .9

5 11 15.5 2 9 23.5 29.5 6 13.5 21 .5 4.5 6 1.5 18.5

Maximum Surface Area of Lake Natural Diverted Water Area at Full Fluctuating Capacity at Catchment Catchment Depth at Supp ly Verge Fu ll Supp ly Area Area Full Supply Level Level Year Level Inundatio n meters km ' km ' 10'm' km ' km ' Commenced 8.5 15 18.5 5 14 45.5 52 213 5 23 33. 5 73 94.5 35 128

132 148 156 38 64 32 41 28 41 9 7 5 240 268

26 43 63 6 26 30 39 5.5 7.5 7 0.5 0.5 7 45.5

687 1,792 2,305 105 510 308 537 706 131 180 145 2,965 11 ,630

396 396 396 262 262 567 567 248 129 344 740 610 735 1290

285 588

583 865 865 735

1912 1922 1905 1962 1949 1966 1937 1952 1967 1969 1971 1972 1972


stalked Hypomicrobium) and aquatic mosses and algae in conc rete cana ls. At Tarra leah th ese are c hiefly Bryum sp. , Fissidens s trictus, and Tridont ium ta smanicum in a d iverse mi cro fl o ra largely co nsisting of diatoms , Gomphonema graci/e, Navicu/a sp. , and Tabe/laria flocculo sa. Th ese bio logical deposits have reduced the effer-cive capac ity of the 20-k m-long (12 -mi le-long) Tarraleah ca n3I from Lak e Kin g Will iam by 10% and in c reased rugosity va lu es in tunne ls and penstocks (where the slim es uni form ly cove r stee l, painted stee l, woodstave , and co ncrete surfaces). Th e resu lt has been a cap italized loss of Aust$3 ,000,000 for the four powe r stati ons in this area alone.

The lake is extensive ly fished for tro ut , chief ly brown (Sa /mo trutta Linn) and rainbow (S. ga irdneri Ric hardson), whi ch apparentl y benefited from t he nutrient gains that fo llowed the in itial and subseq uent floodings and fro m diversions to the lake. There has been some concern during recent years that the fi sh popu lation and growth rate have decreased , but whether thi s decrease has been due to more frequent fishing , lake level flu ctuations, or a decrease of nutrients requires further study. If we exc lude future man-made influences, it is probab le that the lake wi ll slowly return to a senescen t neoo li gotrop hi c co nditio n w ith a decreasing fishery ca pac ity.

Th ese and related prob lems have been investigated si nce 1952. Du ri ng th is tim e, biological and ce rt ain c hemica l aspect s have been identified and examin ed. Tria l and full -sca le c hemi ca l experim entation , in cl uding trout toxicity tests principal ly with co pper su lfate and c hlorin e , has been ca rried out ; and the performance of materials , rugosity vari ati ons , and economi c aspec t s have been teste d and assessed . A comp lete ly effective low-cost so lution using intermitt ent c hl orin e inject ions (1 hour per 15-day period with po we r stat io n disc harg e residua ls of < 0.5 mg /1 of free chlo rine) was prove n after 12 month s of field t rial s, but possible long-term de leteri ous effects on the biota of th e downri ve r lakes and the ir trout fis heries have deferred th e in troduction of these pro ced ures. Extensive c hemica l and limn o logical researc h may succee d in all ayi ng thi s co ncern. Neve rth eless , a tria l pe ri od · of chl orin ati on for 4 or 5 years with monitoring of bio logical parameters appears warran ted on the present evi den ce.

Th e ac idic (pH of 6-7) typica l moorland waters of Great Lake are genera ll y clea r (si li ca scale turb idity of < 5 mg /I and Haze n co lo r of < 1O} , dissolved so lids being < 20 mg /I, manganese being < 0.03 mg /I (genera ll y 0.01 mg /I}, and iron being < 0.2 mg /I. In the small er lakes and tarns, local o rgani c enrich ment results in a max imum mangan ese conte nt of 0.08 mg /I and a max imum Hazen co lo r of 50.

As wo uld be expected in these unbuffered waters , an inve rse re lati o nship ex ists betwee n surface-water in flow rates , pH , and c hemi ca l con tent. Low run -o ffs with their high proportion of groundwater and see page generall y have pH val ues of 7.0-7.5 and tota l dissolved so lids of up to 100 mg / I. Durin g high inflows , pH va lues redu ce to 5.0-5.5 (4.0 for t he Serpentin e River} , and total so li ds redu ce to < 40 mg/I. The eff ect of the weak ful vic- hum ic acids derived from the pl ants , peats, and li tter is ev id ent . Organic co lo ring is generall y high , Hazen max imum s being 50 in the high land lakes and about 150 in the south west rivers. Descripti ons are g ive n of onl y three of the seven ex ist ing large lakes of the Hydro-E lec tri c Comm ission (Tab le 1) and their drainage areas an d probl ems. Two larg e lakes of the th ree be ing co mpl eted are also described. GREAT LAKE (1911 , 1922 , 1967) Pri or to deve lopment for hydropowe r, Great Lake cons isted of two shal low morai nal lakes joined by a middl e reac h except during peri ods o f high inflow. A low masonary dam co mpleted in 191 1 was made obso lete by a mult iple-arc h concrete dam in 1922, whic h ca used th e furth er inundation of marsh es , ope n moorland , and li ght ly timbered areas. In 1967 the 18.3-meter-h igh (60-foot high ) rock-fi ll no. 3 dam was bui lt downstream of th e arch , but th e lake leve l has not yet exceeded th e 1947 peak , whi c h was 0.6 meter (2 feet) be low the arc h crest. There is no permanent snow, but snow falls on about 40-60 days per year , and ra infall var ies from 2300 mm (90 in c hes) on the weste rn scarp to 900 mm (35 inc hes) to the east. At Great Lake , ice form s over some of th e bays about once in 10 years, and severe frosts are freque nt.

Prior t o divers ion of Art hurs Lake to Great Lake in 1966, the Great Lake waters caused on ly a thi n ge latinous sli me ric h in sil ica and iron in pipelines , but mang anous types have since become established. Th e diversion has increased the Great Lake yie ld by about 25%. Other than the initia l leaching of su rf ace laitance and fines, these waters are not aggressive to co nc rete but cause the loss of protec t ive zi nc (galvanizi ng) at approximate ly 0.025 mm /yr (0.001 in ./yr) . In commo n with simi lar experie nces in th e United Kingdom , these pure wate rs wit h th eir low iron , manganese , and organic va lues cause corrosio n problems to un protected stee l, and expensive protection systems to all wetted surfaces are requ ired . LAKE ST. CLAIR (1937) Lake St. C lair is a narrow ove rd ee pened g lac ial lake about 13 km (8 miles) long by 2.5 km (1.5 mile) wide th at is upstream of and in th e Lake King William catc hm ent and that has a maximum depth of about 200 meters (700 feet). Su rro unded by peaks of up to 1500 meters (5000 feet) above mean sea level with heavi ly forested lower slopes and suba lpine up land s, the lake is a major scen ic and to uri st lake and salm onid fishery. A multi ple-gated we ir that is 3 meters (10 feet) high (comp leted in 1937) and a pumping st at ion (completed in 1940) contro l 7.3 meters (24 feet) of the enlarged lake. With a low effec t ive storage to inflow ratio of 0.5 , th e water leve ls.fluctuate in traseasonally, th e min imu m level occurrin g about o nce in 15 years. The inundated ve rge was not c leared , and large q uant ities of trees and scrub were drowned . Before and after be ing regu lated , the lake apparen tly fi shed we ll. Adequate plankton popu lations were reported in the fi rst significant Tasmanian limn o logy survey m ade in 1937-1939 , but later data are meager. More rece nt ly, the limi ted c hem ica l and ph ys ica l resu lts ind icate an unbuffered , slightly acid ic (pH of 6-7) water with extreme ly low sol utes and maximum va lu es of 2 mg /I for ca lc ium , 0.01 mg/I for manganese , 0. 05 mg /I for iro n, and 25 mg /I for total disso lved so li ds. Turbid ity and co lor are also low . Temperatures measured at month ly intervals for 3 nonconsecu tive years show that , from - 46 meters (-150 feet) to -152 meters (-500 feet}, water temperatures are consiste ntl y isothe rm al, the ann ual var iate being 2°C (5.5-7.5°C}; the upper water va ri es seasonall y from 6° to 15°C, t he depth of the upper isotherm extending to about -37 meters (-120 feet) by autumn. Except for the leac hing of weak ce ment mortars and their co rros ive effects on unprotected stee l, these wate rs have not cause d any apparen t eng ineering prob lems.

Sou rces of po llut ants are mainly sheep , wh ich are su mmer grazed at 250-750 per square ki lometer (1 -3 per ac re) on the nati ve grasses of th e unimproved moors; native anim als, c hie fly the marsupial Bennett 's wa ll aby ( Wal/abia rufogrisea ); and approxim ate ly 400 mainl y primiti ve fishi ng shacks infreq uentl y occup ied by spo rting fish ermen . Extensive burn ing has taken place for > 100 years and has resulted in a degenerative environm en\ and widespread but shall ow loss of surface soils and organi c material fro m the res idual peats. More serious soil losses have been prevente d by the prote ct ive effects of the high stone co ntent of the c lay soi l mat ri x and by part ial recove ry during periods of high prec ipit at ion . To date thi s eros ion has not caused a silt problem in th e lake.

Since Lake St. C lair is an old natu ral lake wit h a significant ly altered regi me , su itab ly designed studi es w ith period ic updating cou ld resu lt in its becom ing an eco log ica l bench mark , or re ference lake , from whi ch the behav ior of the newer man-made lakes co uld be corre lated and their future behavior cou ld be predicted.

Th e fi lli ng and emptyi ng cyc les of the lake will vary with the growt h of the power system and hydrologic cond it ions , but, in gene ral term s, th e max imum change in leve l is 1 meter (3 feet) per month , and th e ave rage is 0.3 meter (1 foot) per month . Onl y min or regeneration occurs on the stony foreshore .

Lake Rowa ll an is a she ltered narrow man-made storage 11 km (7 mil es) long in the deep ly incised Mersey Rive r Va ll ey . The inundated val ley floor consiste d of summe r-grazed marshes and grass lands with pockets of dense sc ru b and t rees. Up to 900 meters (3000 feet) above mean sea leve l the catchment is heavily

LAKE ROWALLAN (1967)

15


timbered , principall y with eucalyptus and mixed eucalyptusmyrt le forest. It is un inh abited but is visited by bush walkers , hun ters, and fis hermen , and there is logg ing in the vic in ity of the lake. Reservoir clearing was restricted to the areas adjacent to the dam. Mean annual rainfall varies from 2500 to 1800 mm (100 to 70 inches), and irregular snow falls above the 900-meter (3000-foot) leve l. The storage fi ll ed and spilled in September 1967, 4 months after closure . Hydrogen sulfide in the discharge and extensive fu ngal growth, Sapro /egnia sp., Leptomitales sp. , and bacteria on the bypass valve dissipater were evident in January 1968. Water temperature profi les and chemical analyses taken by the HydroElectric Commission in February 1968 confirmed that the lake had strat ified , wate r temperatures being 17.5°C near the surface an d 7.2°C at the 33-meter (108-foot) depth. The thermocline persisted until late May 1968 and reformed during the following two summers from December to May when it was broken by hi gh inflows with subsequent spill ing. Until mid-1969, only sufficient data were collected to define the situation in general terms, since there was a sli ght possibility that the continuous operat ion of the Rowal lan power station during the su mm er of 1968-1969 wou ld cause suffic ient mixing to rep lenish the oxygen deficiency at depth . When this possibility did not occ ur, a more extensive program of chemica l sampling commenced in August 1969 and has continued sin ce. Since August 1969, data collection has been carri ed out at month ly intervals at four buoyed stations in the lake and at addit ional stat ions in the power stat ion discharge , in the d ivers ion pondage 9.65 km (6 miles) downstream (Parang ana), and downriver. Full chemical sampling has been taken from two to four depths at each station in the lake ; the number of samp les taken depends on water depth bu t inc ludes a samp le fro m 0.6 meter (2 feet) above the lake bottom . Bacteriological exam in at ion of certain discharges for p late count, co li-aerogenes, and fecal coliforms (E. co lt) were also made . Th e pressure conduit through the bottom of the dam is in situ concrete connecting the low-level outlet to a surface steel penstock ; internal paint systems are epoxy on a section of the concrete and spun coal-ta r ename l and tar epoxy on the steel. Inspect ions in August 1968 and subsequent ly showed that all internal surfaces were coated with 4 mm (0.15 inch) of red brown ironrich slim e with high organ ic content, principally bac illi , yeasts , and some fungi. Gallionel/a and ch lamydobacte ri a were not evident , whereas Hypomicrobia were only present in small numbers . The hypolimnionic enrichment of the lake has increased the iron and manganese solutes from 0.1 mg /I to 3.0 and 0.5 mg /I (maxim um s), respective ly; the dissolved ca rb on dioxide from about 3 mg /I to 21 mg /I; and the disso lved su lfide to 0.3mg /l with low or no DO (disso lved oxygen) at depth for 3-4 months per year. From limited evidence it is apparent that the plankton numbers have not sign ifi can tl y increased, and there are no signs of any deleterious effect in the epilimnion. Phosphate is about 0.06 mg /I as PO, . During summer the noxious odor of hydrogen sulf ide is evident at the power station and for some 5 or 6 km (3 or 4 miles) downstream; river gravels are coated with iron precipitates , and some small fish (trout) kills have occurred in this reach. However, the ri ver is shall ow and fast flowing , and reoxygenation occ urs in the fi rst few ki lometers ; atmospheric dispersion of these weak gases is rapid. There is no evi dence of deteriorat io n of hydrau li c mac hi nery , concrete surfaces , or painted steelwork (e ither im mersed or exposed) other than the formation of sulfide oxides on silver relay co ntacts . Artificial destratification that would reduce the downstream iron co ncentration , in crease discharge wate r tem peratures, decrease the lake surface evaporation , and have aesthetic and limnological benefits is currently under consideration. LAKES PEDDER AND GORDON (1972) Situ ated in wet , uninhabited , and und eve loped southwest Tasman ia, the Gordon River Power Development (stage 1), when it is completed , wi ll consist of a deep underground power station wit h an installed capacity of about 725 Mw , four dams , and two large man-made lakes. Lake Gordon w il l have the largest live storage in Austra li a.

16

Mean annual rainfall varies from 1800 to 3300 mm (70 to 130 inches), and there is hail and infrequent snowfa lls at the reservoir e levat ions and nonpermane nt snow on the peaks. Th e rocks of the basin are Precambrian and Paleozoic , extensive g lac ial outwash forming large marshy flats at about 275 meters (900 feet ) above mean sea level. Large areas of the catchme nt co nsist of leac hed low-nut ri ent shall ow so il s, grave ls , and roc ky o utc rops with peaty sedge lands , heaths , and low shrubberies. Howeve r, in Lake Gordon's catchment basin and reservoir and to a lesser extent in the eastern portion of Lake Pedde r, there are sign ifi cant forests of eucalyptus and mi xed eucalyptus and rai n forest (chiefly myrt le). Scattered small stands of trees occur on the hills , and patches of wet sclerophyll occur on the watercourses. Th e Gordon Rive r sou rce is ad jacent to Lake King Wi ll iam , and th ere are subalpine eco log ica l areas in this region. There are no private lands in the catch ment bas in s, and the required works and sto rage areas are now vested in the HydroElectric Commission , the ad joining Crown lands be ing part ly scenic reserve included in the large southwest fauna district . Because of these restrictio ns, domest ic anim als and exotic plants are not permitted in the area, and hun t in g is pro hi bited . Lake Pedder wi ll be formed by a 40-meter-hig h (130-foot-h igh ) dam on the Serpent in e River with a bottom out let for occas ional flood re leases, a 45-meter-high (150-foot -high ) dam on the adjacent Huon River, and a 15-meter-high (50-foot-high ) sadd le dam. From this common lake the conjoined waters wil l be diverted to Lake Gordon via 3.2 km (2 miles) of shallow c ut and canal. The existing Lake Pedder , an attractive 10-k m' (2500-ac re) shallow natural lake , will be drowned in the en larged lake. Lake Gordon , the headwater reservoir for t he Gordon power station , will be formed by a dam approxi mately 137 meters (450 feet) hig h . Both sto rages will be practicall y 100% regulated , inflows passing through the underground station via a sing le intake shaft at an elevation of 254 meters (830 feet) above mean sea leve l in th e base of the 76-mete r-hi gh (250-foot-hig h) conc rete towe r stand in g in Lake Gordon. Extensive perimeter c learing wit h burning or bu ri al of the debris is p lann ed at Lake Pedd er, where the normal operating range is 1.5 meters (5 feet). However, because of its size , the operating range, and the related cost, c learing in Lake Gordon wi ll be restricted to smal l areas adjacent to the dam and the main access road . Both storages , whi ch will take seve ral years to fi ll , have deeply indented bays w ith partly enc losed sectors , and several years work is anticipated before the littora l debris is co llected and burnt. Mount Sol itary (12 km ', or 3000 ac res) w ill be th e largest of the numerous island s and is ideall y situated for future use as a permanent primitive eco log ica l reserve restricted to scientific studies. Prior to the construction of access roads for power development , these areas were visited by 300-400 bush walkers per year. Tourists visiting the area are now about 25,000 per year and are increasing , whereas the accessible wi lderness areas have bee n co nsiderably extended. Fauna , flora , and limn o logical studi es , principally of the Lake Pedder storage area, have been carried out , and there is now cons iderab le scie nt ific interest in w hat was previously an alm ost tota ll y neg lected region. The relevant init ial study was made for the Hydro-E lectric Comm ission in early 1967. Although Tasmania is not in a region of sign ificant seism ic activ ity, the co mmi ssion 's eng in ee rs and geologists have carri ed out stud ies for possible earthquake effects following the fillin g of Lakes Gordon and Pedder. A station forming part of the state seismic grid is being insta lled at Gordo n Dam toget her with th e instrumentat ion of the nearby Lake Edgar fa ul t to measure microseismic activity. The state seismic grid has also been extended and improved. Chemical ana lyses and physical data co llection from the relevant surface waters commenced in 1966, and air, ground , and water exposure tria ls of selected metals and paints commenced at fou r local and eig ht related sites in 1968. It was apparent from the known water chemistry (pH of 4-7; maxim um s of 1.0 mg /I for iron , 0.05 mg /I for manganese , 10 mg /I for ca lcium , and 10 mg /I for dissolved CO, ; and Hazen co lor of 150) and from the pre limi nary resu lts of the testing materials that specia l des ign and const ru ction measures would be required in these lakes to avoid poten-


tially severe corrosion and concrete deterioration problems. The c hief factors inf luencing the prediction for engineering purposes of the chemical and biological behavior of these lakes are the long retention times without discharge during initial filling , the immense quantities of organic matter that will drown , and the chemical balance of the mixed waters with appropriate adjustment for the changed environment following inundation . An additiona l factor is the isolation of the deep water at the principal dams (Serpentine and Gordon including the power intake) from win d and current due to the near-topograph ic closure of these smal l sectors of the reservoirs . Th is work has been a major factor in determining the relevant design criteria for the components of the immersed structures regardi ng their safety , ma intenance , and cost. Principa lly , these structures requ ire the extensive use of austenitic stainless steel and plast ics; cat hodic protection of certain deep structures; special regard for the removal , maintenance , or replacement of deep hydraulic equipment; and the production of dense rich conc rete , part icu larly in certa in situations. The main paint systems adopted and proved by the Hydro-E lectric Commission in other areas are considered satisfactory in Lakes Gordon and Pedder, but the use o f zinc galvaniz ing (inc luding in the sp lash zone above ground) , copper, and aluminium has been restricted. Ch lorination of the coo ling water for the station is being examined to contro l th e expected slime deposits in these conduits and on the screens. Although subject to sudden weather deterioration , Lakes Gordon and Pedde r wi ll be centers of major tour ist attraction and wi ll provide both termina l points and access ways to these previously inaccessible primitive regions . The biota-deficient acidic rivers of th is reg ion are c urrent ly unsuitable for sport fisheries , but it is an-

·ii

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ticipated that the impoundments will have pH minimum of 5-5.5 and biological enrichment wi ll resu lt in a supermesotrophic state and a satisfactory environment for fish. Eutrophication of the upper biotope is not expected . CONCLUSION It is evident that some of the engineering matters briefly described in this paper and the ir relat ionships to the chemica l and biological aspects of the building of major lakes require further work. It is also c lear that considerable applied research and methodo logy is needed to evaluate the basic chemical , physical , and limnological condition of Tasmanian lakes with emphasis on determining the contro lling parameters and their long-term effects . Although some good progress has already been made , a satisfactory solution to the prob lems of non-integrated catchment management for Tasmania is required , and multidiscipline research and assessment to evaluate the various factors are needed. Acknowledgments. The author wishes to acknowledge the laboratory work done for the Hydro-Electric Comm ission by Mr. M. H. R. Shipp, B.Sc., A.R.A.C.1., government analyst, from which the chemical data used in this paper are largely derived and to thank Sir Allan Knight , CMG, ME, B.Sc., B. Comm ., FIE (Australia), Commissioner of the Hydro-Electric Comm ission, for permission to publish this paper.

Abridged edition of paper written December 1970.

Mcfie, Henry, Geophysical Monograph No. 17. Pages 56-62, 1973 Copyright by American Geophysical Union.

A QUEENSLANDER RHODES SCHOLAR

~

1' p. I

•l°oo·

The recent announcement of the 1975 Rhodes Sc holar is of interest to A.W .W.A. Members. Mr . Peter Kennewel l, who is studying Science at the Australian National University , Canberra , is the so'n of Mrs. Josie Kennewell . Chemist with the Brisbane City Council. and a member of the Queensland Branch. Peter completed his primary and secon dary education at Nudgee Co ll ege , Brisbane where he took first place for the State in both Junior and Senior examin;.,tions .

FRENCH OFFER SCHOLARSHIPS Vl

0 C. -I :I:.

m

:,:, 'Z.

Each year the French Government offers a limited number of sc holarships to enable Australians working in professional and technical fields to visit France to further their experience through observation and , where appropriate, participation. An information sheet giving details of the award is avai lable from the Federal Secretary.

INSURE AGAINST DROUGHT

Fig 1. Map of Tasman ia showing the hydro-e lectric power developments and the comp leted and proposed large storage lakes (sca le: 1 cm = 25 km . approximately).

You may have received this issue FREE! .. . $4 per year wi II ensure that you continue to receive ' WATER '.

17


CONFERENCE CALENDAR

46TH ANZAAS CONGRESS Canberra, January 20-24, 1975

INTERNATIONAL ASSOCIATION FOR WATER POLLUTION RESEARCH 8TH INTERNATIONAL CONFERENCE SYDNEY 22-27 AUGUST 1976 Officia l Open ing: The Opera House Venue: The Wentwort h Hotel

CONGRESS SECRETARIAT G.P.O. BOX 2609, SYDNEY, N.S.W., 2001. Telephone (02) 27 6940 Pre limi nary Brochures and Details regarding Registration and Submission of Papers are available from the Secretariat and from: Or . M. Flynn , Secretary-Treasurer,I.A.W.P.R. Australian Committee I.A.W.P.R. G.P.O . BOX 2609, Sydney, 2001. Al l A.W.W.A. state and Federal Secretaries . The A.W.W.A. is a member of the I.A.W. P.R. and recommends your support for the 8th International Conference .

The 46th ANZAAS Congress is being held in Canberra from Monday 20 January 1975 to Friday 24 January 1975. The theme for this year 's Congress is " Science , Government and the People ". In addit ion to various Congress wide activ it ies a number of specialist sect ional comm ittees have plann ed programmes of interest to more limited groups of registrants . There is an Engineering Section (Section 5) and the Sectional Committee is being co-chaired by Professor H. E. Green of the University of New South Wales at Duntroon an d Professor S. Kaneff of the Australian National University . Committee Secretary is Mr R. F. Goldfinch of the Department of Housing and Construct ion. Mr A. S. Reiher, Secretary , Department of Housing and Construct ion, has been invited by the Committee to act as Sectional President and he has kindly accepted. The Section 5 Committee have sought to deve lop a pro gramme around five sub-themes of engineering interest which are related to the overa ll Congress theme . At the opening Monday afternoon session the President w ill de liver the Presidential Address on " The Austra li an Construction Industry in the Service of Science , Government and the Peop le" and this will be followed by a session devoted to Water Resources. Sessions on subsequent days will cover Food Production , Computers in the Study of Complex Systems , Educational Technology and the Engineer, the Law and the Citizen .

A.W.W.A. SUMMER SCHOOL Applications have closed forthe Summer Schoo l onthe theme " Water in the Urban Environment " to be held in Canberra from 3rd to 7th February, 1975. For those who are unable to attend the School , extra cop ies of the lecture notes will be available for purchase fo llowing the School. Each set of notes wil l comprise all the lecture material distributed to parti cipants at the School, bound in two loose leaf viny l covers. The notes will be sold only in comp lete sets priced at $20.00 per set with postage paid within Australia . Persons wishing to obtain copies of the notes should submit their order and cheq ue to:

The Hon. Secretary, A.W.W.A. Summer School, P. 0. Box 359, CANBERRA CITY, A.C.T. 2601.

'Occurrence of Nitrates in Groundwater' R. L. Cliaby Vol.1. No 3. Sept.1974. It is regretted that acknow ledgement was not made of the work of Mr. J. D. Waterhouse the Department of Mines hydrogeo logist responsib le for organising and carrying out the po llution assessment programme . Mr. Waterhouse has prov ided the fol lowin g ad ditional c omm ent.

" Treatment , Recyc le, Reuse and Disposal of Wastes ."

The interpretations made are not d isputed (my report dated 22.6.73 includes them) , but they are incomp lete and misleadin g. For example there is a strong correlation between high nitrate concentration and land-use near the borehole , suc h as stockyards, troughs, sept ic tanks etc ., ref lecting essent iall y locali zed effects, not aquifer contaminat io n. The log-transform p lot mere ly reflects the distribu t io n of sampled bo re-ho les with ad jacent env iro nments likely to cause locali zed co nta min at io n . It furt hermore takes no account of the vary ing boreho le envi ron ments with the 3Km squares from wh ich the contoured " va lu es " are derived. The important resu lt of my study is t hat high nitrates near the city of Mount Gambier do reflect aquifer contam ination caused by subsurface waste disposal and those in the rural areas te nd to ref lect locali zed effects suc h as proxim ity to a stocktroug h .

Plenary sessions covering env ironment study , planning, protection and legislation , and departmental sessions on waste management in the fields of:- Mining and metals Extraction , Forest Pulp and Paper, Manufacturing Industry , Food Processing , Chemical , Petroleum , Agri c ulture and the Urban System.

PLEASE NOTE

Deliveries will be made following completion of the Summer School and receipt of payment in full.

The 1975 Chemical Engineering Conference Mildura, Au~ust 20-22nd , 1975.

Further detai ls and instructi ons for authors of papers for the Conference , available from Dr. D. V. Boger, Dept. of Chemical Engineering , Monash University , Clayton , Victoria 3168. Sponsors - I. Ch.E. in association with LE .Aust., RAC .I. and A.I.M.M.).

18

EDITORS NOTE

For this first issue you may have rece ived a comp li mentary copy . Shou ld you wish to continue to receive the quarter ly issues , you are inv ited to comp lete and return form on page 22.


UNIQUE WATER SUPPLY PROBLEMS IN THE NORTH WEST OF SOUTH AUSTRALIA Dr. 0. Fuller and R. Shepherd * 1. The Area The "North West Area" is bounded on the north and west by the State boundaries, east by the existing north-south railway line to Alice Springs and south by the Everard Ranges. It contains station properties , a mission , government reserves , the North West Aborigina l Reserve and one town , Oodnadatta, on the eastern boundary. The North West Reserve was proclaimed in 1921 , 1935, 1941 and 1964 and consists of:Name

Area

Established by

.Amata

27,620 sq. miles

Ernabella

2,400 sq. Presbyterian Mission miles Presbyter ian Mission

Fregon lndulkana

Mimi li

9,000 acres

2,350 sq. mil es

Th e Government of South Australia (Formerly Musgrave Park)

The Government of South Australia (Formerly part of Granite Downs Station) The Government of South Australia. Known as Everard Park Station (includes Betty 's Well)

FREGON The supply co mes from one bore located at a higher level than the settlement. The water is stored in a large tank and reticulated to the settlement. There is no chlorinat ion and potabi lity is acceptable . INDULKANA Here the problem is not only quantity but quality . Four bores are in use plus a desalination plant and a tank syste m for mixing to produce an acceptable end product . Data for these four bores are shown in the accompanying tables : INDULKANA BORES

Date Population Established

1961

1972

DETAILS

340

Date of samp le Depth of Bore Water Level Depth Water Cut Depth of casing Casing size Pump Equipment

1937 520 1961

Supply in G .P.H.

1967

200

Supply in litres per hour

No.1

No.3C

No.4

No.6

7/9/70 2/9/70 1/11/70 7/9/70 137'-9" 116' 220' 110'-6" 38'-6" 170'-6" 23' 56' 98' 44' 182' 26 ' 115' 42' 220' 91' 5" 5" 6" 6" Pump Windmill Windmill Pump Jack Jack 480 750 300 600 2182

3410

1364

SPRING

15/9/70 Ground

Not Known

2728

DISSOLVED SAL TS

Total Salts (mg / /) 1972

100

INDULKANA is 160 miles north west of OODNADATTA ERNABELLA is 60 miles east of AMATA

2. Water Supply Water has been an important criteria in the selection of locations , so a brief out lin e of the current water supply at each settlement is appropriate:AMATA The supp ly comes from two bores within half a mile of the settlement and ttie water is pumped from the bores by diesel pump jacks. It is pumped directly to overhead tanks in the settlement. There is no chlorination of the supply.

There are holding tanks at the bore heads , but these are used to supply drinking water to cattle. Potability is acceptab le and no other source of supp ly except rain water tanks in the settlement is used. ERNABELLA This is supp li ed by three bores situated close to the sett lement. A fourth bore is operating but is not used because of the distance from the settlement and sufficient water for the present is available from the three in use .

The water is pumped to, and mi xed in , large tanks used to supply a pressure head. There is no chlorination of the supp ly. Potabi lity is acceptab le and rain water tanks are the only other source used in the settlement. â&#x20AC;˘ Dr. Oliver Fuller. Department of Health . South Austra lia. Mr . Reg . Shepherd , Department of Mines (SA), Hydrogeology Section .

Chloride Sulphate Bicarbonate Nitrate Fluoride Sodium Potassium Calcium Magnesium

1490 & 1587 700 185 335 241 19 144 133

1760

2593

2348

2945

535 295 625 trace

735 930 220

865 440 470

404 16 92 108

479 18 137 189

495 39 130 149

965 819 239 6 0.6 530 17 163 205

3. The present problem The slow pattern of change from a nomadic existence to a dependant one centred on a settlement with just sufficient water for its original needs has altered drastically in the past five years and particularly in the last two years.

There has been a move toward Abor iginal co ntrol of the settle ments through Aboriginal Counc il s, with the State Departments of Community We lfare , Education , Health and Public Buildings providing the services required by the commun it y. Funding of these State Departments by the Australian Governsewerage systems (common effluent drainage), waste disposal, power generation , road construction and most significant of all a greatly increased demand for a reticu lated water supply. This sudden influ x of funds will result in an extensive building program by all State Gove rnment Departments and by the Aboriginal groups themselves . This will in turn mean a need for sewerage systems (common efflu ent drainage) , waste disposal, power generation , road construction and most significant of all a greatly increased demand for a reticulated water supply .

19


At Ernabella there are already vegetable gardens and c itrus orc hard s with surplus destined for Alice Springs. Poultry production and an abattoir to serve all the other centres , are likely projects in the near future . The new health centres will use a min imum of 3,000 litres a day - this is more than one hour's pumping from all lndulkana's bores.

II. Mimili (Evarard Park) No groundwater survey has yet been made of thi s area , but it appears that supplies are availab le, mainly from al lu vial sediments surrounding the granitic rocks of the Evarard Ranges . Stock water is required in a number of areas , and at least in some of them, there are possibi lities that supplies will be obtained.

As there is already a problem of quantity and quali ty, water su ppl y mu st be the limiting factor in the overal l planning for the area.

Ill. Ernabella, Fregon Successful bores at Ernabe ll a were dril led into allu viam adjacent to Ernabel la Creek. Th e aquifer has a very limited extent occupying a long narrow valley. During 1970 fiv e bores were drill ed , main ly within th e ce ntral part of t he valley and of these three we re successful.

Th e Australian Government is supporti ng an Aborig ine at Ernabe ll a with finan ce and a boring plant to become the we ll d rill er fo r the area . The new railway lin e to Alice Springs shou ld pass w ithin five mi les of lndul kana and wate r cou ld be brought in by tanker . For the other reserves , water is the real limiting fac tor to all future growth and development of adequate supplies must be ensured before any extensive planning or development can take place.

4. Provision of future water supplies (a) Surface resources Rainfall is low and erratic ; rainfall maps of the area show ¡average ' rainfall of 6-8 inc hes per year. However, variation from the mean annual rain fall may be at least 50%. On the other hand evaporation is ve ry high , exceed in g 80 in ches per annu m over most of the area. Condit ions are eve n more extreme in the sand dune co untry so uth of the Musgrave Ranges . Thu s run-off , when it occ urs, persists tor on ly short periods in the form of wate rh oles in the c reek c hann e ls. Most of the run-off is lost by evaporat io n or transpiration with on ly a very small pro port ion reaching the groundwater. In the vicinity of the ranges ra infall resulting from thunderstorms may cause heavy run-off , which contains a large proportion of silt. Thus dams built on watercourses tend to si lt up rapidly .

(b) Underground resources Investigations for groundwater commenced by the Department of Mines in 1955 and showed that potab le gro und water was avail able in ce rt ai n areas. Drilling with Mines Department rigs co nt in ued on th e var ious reserves in termitt entl y until 1971 . As was expec ted the dril lin g resu lted in a high proportion of failu res fro m a total of 85 bores , 30 we re regarded as successful. Most bores were comp leted in alluvial sand s but in some areas water supp li es were obtained from fracture or shear zones wit hin basement rock . Details of investigations in the various reserves are as fo llows: -

!. lndulkana This reserve whi ch has a area of only 31 sq uare k ilometres is located on the lndulkana Range . The first series of 11 bores was dril led in 1967 but all were regarded as unsuccessfu l as th ey yie lded saline or brackish water. Several bores were dri ll ed into the Ordovi cian Lim estone and sandsto ne within the range and also into the all uvium of the lndulk ana Creek. Several of these bores also penetrated ¡ .ower Proterozo ic gneiss but in al l cases salin ity was too high fo r dri nking water. Th e lowest recorded sal_inity was 3700 mg / /. In 1970 sites were selected wit hin slates and quartzites of the Ade laide System (Upper Proterozoic). A tota l of 7 bores were dril led , mainly in slates, both north and south of the range and of these 4 were regarded as successful. Salinities originally ranged fro m 1260 (No.1) to 2000 (No.6) mg / I but have increased since 1970 by about 300 mg / /. Yields are low , rang in g from 0.4 to 0.9 lit res pe r second. Because of the low and erratic rainfa ll ru n-off, intake occurs on ly rarely; therefore there is a dang er th at with increasing deve lopm en t of the groundwater, supp lies w ill beco me dep leted. It may be possib le to obtain additional supp li es on the south side of the range but th e qu antiti es avail ab le are lim ited. " Mining " of the groundwater may already be occ urri ng in view of the apparent sal inity increase since 1970. To obtai n add iti onal supplies it may be necessary to carry out desalination of the more saline groundwater. Other possibilities include the stori ng of run-off in the sands of the lndul kana Creek by suitab le structure across the cha nnel.

20

Salinities of th e groundwater are low , averag ing 500 mg / / and yields range from 0.3-2.5 litres per second - simi lar results have been o bt ained in new bores drilled since 1970. Such relatively large supp lies and low salinity however, do not indicate large reserves . Although intake apparently takes place read ily , its irregu lar occurrence and the limited extent of the aquifer, indicate that the safe yie ld is probably less than 15,000 litres per day . For comparison the total yield from successful bores in the Ernabella area amounts to approxi mately 30,000 li tres per day , if they were all pumped continuously. A geophysical survey (resistivity) has been carried o ut in the Ernabella area. This has given reasonable indi cat ions of areas of deepest cove r, because the depth to basement rock ca n be determined fairly acc urately. Howeve r, it is not poss ible to accurate ly posit ion the upper surface of the aquifer. Geophysics is therefore usefu l as an aid in locati ng sites tor bores. At Fregon , four bores we re drilled wi th two being successfu l. Fregon is located in a re lativ ely fl at area adjacent to the Officer River. Previous drilling has shown that bores drilled close to the river bed had a relatively high sa linity, but a bore in use in 1970 located in a depression a short distance east of the river , yie lded potable water. During 1970 seve ral bores were drilled in depress ions within the sand du nes on the east side of the Officer River. These were successfu l, but th ose dril led to the west of the river channel we re of high sal init y. Yields of bores in the Fregon area are re lative ly large , 1.9-2.7 litres per seco nd and it mig ht appear that these are larg e rese rves of groundwater. However, much of this water is believed to be sali ne. Overpumping , or exceeding the safe yie ld wou ld result in a rise in sa linity. Additional supp lies might be obtai ned in this area by dri ll ing in some of the depressions .

IV. Amata The settlement is located in a broad valley and it was considered that the best prospects were in the alluvium . However , th e alluvium was found to be very varia bl e in th ick ness and basem ent rock occurred at shallow depth in many areas. This is shown by the dri llin g results as on ly 3 bores of 11 dri ll ed were successfu l. Salinities of t he successful bores rang ed from 630 to 970 mg / I and yield s from 0.45 to 1 li tre pe r second . A resistivity survey has been made across the val ley north of the sett lement and there are indi cat ions of deep al luvium , possi bly conta in ing an aqui fer along this traverse. Additiona l supplies may be obtained by drilling where the indications are best; however, in co mmon with other areas of the north west the sate yie ld of the aquifer is small. This is particularl y true at Amata where the aquifer does not occ upy the whole valley but is of limited extent.

V. Karamata This is a large but isolated granite outcrop about 65 ki lometres (40 mi les) south of the Mann Range . It is an area of sac red ground to the Aborigin es and a water su ppl y is required there. Four bores we re dri lled arou nd the hill and onl y one was regard ed as su ccessfu l. A yie ld of about 40 litres per hour was obtained , th e sali nity being 660 mg / /. The bore was subsequent ly equipped w ith a hand pump as it could prov ide small quantities of drinking water. It is doubtful whether additional suppli es co uld be developed in this area.

Turn to page 22


Construction of the Molonglo Valley Interceptor Sewer (M.V.I.S.) Th e National Capita l Deve lopment Commission has awarded a contract to Jo hn Ho ll and (Ho ldings) Ltd . for co ristru ction of an interceptor sewer from a point ad jacent to the existing Weston Creek Sewage Treatment Plant to the site of the pro pose d Lower Mo longlo Water Quality Cont rol Centre . The sewer was designed by th e A.C.T. Regional office of the Australian Department of Housing and Construction. Construction of the sewer is being supervised by the Department. Total length of sewer co nstruction is approxim ately 14,940 metres. Th e project has been di vided into four sections numbered consecutive ly from the upstream end as fo ll ows . Section 1 Section 1 is about 960 m long and comprises:(a) A 1950 mm nominal diameter pre-cast concrete sewer pipeline having a grade of 0.207%. The pipes are rubber ring jointed . Th e sewer wi ll be connected at the upstream end of Section 1 to the Tuggeranong Sewer Tunnel whi ch is current ly under construction. A Vortex Drop Structure with a drop of abou t 4.3 m will be located near the entrance of the tunn el. This drop structure wi ll connect the existing Canberra Main Outfall Sewer to the M.V.1.S. A further co nnect ion will also be made in the vicinity using a Vortex Drop Structure wit h a drop of about 4.6 m to connect the existing Woden Trunk Sewer to the M.V.I.S. (b) The downstream end of Sec ti on 1 con sists of a 1950 mm nominal diameter co nc rete sewe r bridge whi ch spans the Mo longlo River in six (6) equal spans each of approximate ly 6.1 m. Th e deck co nsi sts of a conc rete section co ntain ing a liner formed by precast re- inforced co ncrete pipes ca rried on piers anc hored to the foundation rock.

'-~ - -

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The top of the bridge will be constructed to carry vehicu lar traffic . The Molonglo River is subject to substan tial flooding and water may rise about 9.1 mover the top of the bridge. Section 2 Section 2 cons ists entirely of a tunnel , 1950 mm nominal diameter, 1570 m long , concrete li ned , on a grade of 0.207 %. This structure is known as the Ryan Tunnel. Section 3 Section 3 comprises :(a) A 2550 mm nominal diameter pipe sewer about 9140 m long and grade of 0.1587 %. The pipes are doubly rein forced and have a wall thickness of 175 mm. The pipes are laid on concrete bedding . Pipes are laid as straights or c urves each having radius of 30.48 m (100 ft .) or 60.96 m (200 ft .). (b) Six stee l pipe bridges with spans of various lengths, but having a maximum of approx im ate ly 27.4 m. Total length of sewer pipe bridge will be about 751 m. (c) Approximately 231 .6 m of cast in situ co ncrete conduit. Section 4 Section 4 consists entirely of a tunnel ,. 2550 mm nominal diameter, 2195 m long , co ncrete li ned on a grade of 0.1487% .

Pipelines Seismic surveys , auger boring and backhoe holes along the route of the pipelines coupled with surface mapping of geological features showed that some 2/3 of the route could be in Mount Painter Porphyry and the remainder mostly in dacite and rhyodacite . Rock outcrops for about 1% of the route , elsewhere there is soil cover with occasional rock fragments. Backhoe holes suggest that there is an average of about 1 m of soil cover on the route . Se lected soi l and highly weafhered rock from the excavation will be allowed for use as backfill. No ground water was encountered in any of the auger holes , although it was expected some inflows may occur during trench construction due to spring action. Care of the Site The pipeline of Section 3 wil l be located on the right bank of the Molonglo River. The river and its environs are used for recreation and , being of some environmental significance , the Contractor will be required to exert care in excavation and restoration processes . Construction Procedure The pipe trench has been excavated using conventiona l means . The formwork for the concrete positioriing and initial support crad les is positioned by a surveyor. The supports are at 1,219 mm centres. To minimise the possibi li ty of cracking , resulting from concentrated loads at these supports when the bedding concrete shrinks away from the pipes, the upper surfaces of the crad les are covered with a compressible material (Cane-ite) before the pipes are laid .

INVESTIGATIONS FOR THE SEWER 1. General A number of diamond drill ho les were sunk along the route of both tunne ls. Also geop hys ical traverses were carr ied out along the entire length of both tunnel lines and in selected areas of the pipelines. Auger ho les and test pits at approximately 50 m spacing were sunk along the route of the pipeline .

The 10 tonne concrete pipes are tra nsported to the side of the tre nch on a special pipe carrier capable of rotating the pipe about its axis so the correct orientation is achieved before a crane lifts it into position . Continued overleaf

Tunnels A preliminary geological report indicated that dacites , rhyo li tes and rh yodacites would be encountered in both tunnels with about 15% of their lengths in weat hered rock .

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21


Continued from page 20 VI. Mt. Davies Seven bores were drilled in this area in 1970 for a possible settlement . and a replacement for the airstrip ¡bore . The latter is located in a broad alluvial flat in which one aquifer consisting of coarse sand was known to occur. Yields from bores near the airstrip were tested at 3.5 litres per second with salinities of approximately 700 mg / /. Of the seven bores drilled five were regarded as successful although all yielded potable water but in those regarded as fai lures, the yie ld was low . Two of the successful bores entered the basement rocks and the water was apparent ly obtained from them .

There are possibilities for additional supplies of groundwater in this area and Geophysics may indicate sites of thick alluviam. However, as in al l other areas of the North West the yield of groundwater cannot be increased beyond the safe yield and must remain low compared with the higher rainfall areas of the south.

Other sources of potable water Groundwater of low salinity was located by an oil exploration company in sediments of the Officer Basin south of the Birksgate Range (70 miles south of Mann Ranges) .

Water of 570 mg / / occurs at a depth of 170 metres and in an adjacent deep well, water of 1960 mg // occurred at a depth of 433 metres . This is believed to be fossi l water, extent unknown , but it represents a resource which co uld be deve loped . Summary Enlightened and liberal policies of soc ial development of th e aboriginal peoples of the North West Area must take acco unt of the necessity of ensuring adequate water supplies in an area where rainfall is low and erratic. Surface supp li es cannot be relied upon and the safe yields of underground water basi ns is inadequately understood at the present time although, clearly, underground supplies are quite limited .

MOLONGLO SEWER CONT. The pipes are " hinged " into place and pu lled along with a crane to seat the rubber ring joints . The cont inuous unreinforced concrete bedding is poured after t he pipes are correct ly posit ioned. Anchor bars connected to th.e pipe by a threaded inset are embedded in the co nc rete bedding. The 30.48 m (100 ft .) and 60.96 m (200 ft.) radius curves are constructed using pipes with a 4° 35' skewed spigot. The skew is provided by using a special built in skewed spigot ring during the manufacture . The 30.48 m radius curve is achieved by laying a series of pipes with skewed spigots whereas the 60.96 m radius curve alternates straight pipes with skewed spigot pipes. It is anticipated that the sewer wil l be comp leted by January , 1976. The Co ntract price accepted for work is:Construction: $7,210,828 Pipes : $1,965,999 TOTAL: $9,176,827

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Water Journal December 1974  

Water Journal December 1974